I Am Having Problems With My Lower Legs, Feet, And

I am having problems with my lower legs, feet, and ankles swelling, red spots on both shins with heat, cramps, and tingling in my feet. I have had ankles and feet swelling for over 6 years now. I am diabetic - my doctor checked my blood and urine. Sugar is good and the protein build up in kidneys has not progressed. I sit entirely for prolonged hours 6-8 at a time and as many as fourteen with only bathroom breaks (2-3) daily. So my diabetes as a cause has been ruled out but what else can be causing it.